# Sermorelin Dosage and Half-Life: Doses Studied in the GHRH(1-29) Literature > Sermorelin dosage in the research record: doses studied in children and older men, the ~10-12 minute half-life, routes studied, and why bedtime administration was used. Studied-in framing, no recommendations. A research-context record of how GHRH(1-29) was administered across the published studies — what was given, to which population, by which route. Not a usage recommendation. ## Before the details This page reports how sermorelin was *studied*, not how anyone should use it. It gives no human dosing instructions. Every figure below is a dose that appeared in a published study, with the population and route it was used in — because a dose only means something attached to who received it and how. Sermorelin's short stay in the blood (a half-life of about 10-12 minutes) shaped most of these designs, which is why timing and route get as much attention here as the numbers themselves. ## Sermorelin dosage: doses studied in the GHRH(1-29) literature Sermorelin dosage in the research record clusters by purpose. The pediatric efficacy study used 30 mcg/kg/day subcutaneously at bedtime in GH-deficient children, accelerating first-year height velocity from about 4.1 to roughly 7-8 cm/year [1]. Aging research in older men used 0.5 mg and 1 mg subcutaneously twice daily for 14 days, producing dose-related rises in 24-hour GH and IGF-1 [2]. Diagnostic GHRH stimulation historically used a single intravenous bolus — commonly around 1 mcg/kg — to test pituitary GH reserve. Pharmacokinetic work used intravenous doses of 0.25-2 mcg/kg, with measurable GH release from as little as 0.25 mcg/kg and maximal release at 1-2 mcg/kg [3]. A dose-response study of the GHRH analog [Nle27]GHRH(1-29)-NH2 in normal men found dose-responsive GH stimulation across intravenous, subcutaneous, and intranasal routes, but required a tenfold higher subcutaneous dose and a thirtyfold higher intranasal dose to match the intravenous effect — a direct illustration of how route changes the dose required [12]. These are studied doses in defined populations, reported as research context only. ## Sermorelin half-life and pharmacokinetics Sermorelin's half-life is short: on the order of 10-12 minutes in plasma after intravenous administration [3]. GHRH(1-29) is rapidly eliminated — yet, despite that clearance, a single dose elevates serum GH for roughly 3 hours, because the GH pulse it triggers outlasts the peptide itself [3]. That brevity is the engineering problem the whole analog family was built to solve. The native peptide's short life motivated longer-acting designs — the D-Ala2 substitution that resists one cleavage enzyme, and the Drug Affinity Complex (DAC, an albumin-binding group) behind CJC-1295 with DAC — which sustain GH and IGF-1 over much longer windows [3]. The [sermorelin vs CJC-1295](/vs-cjc-1295) page works through that native-versus-stabilized contrast in detail. Pharmacokinetics also constrain route: intranasal bioavailability of GHRH(1-29) was only about 3-5% [3], which is the research basis for why oral and sublingual sermorelin products are widely criticized as ineffective. ## Routes studied Three routes appear in the record. Subcutaneous injection was the primary route in the efficacy and aging studies [1][2]. Intravenous administration was used for diagnostic GH-stimulation testing and for pharmacokinetic work [3]. Intranasal delivery was studied historically but showed only ~3-5% bioavailability [3], and the cross-route comparison of [Nle27]GHRH(1-29)-NH2 confirmed that subcutaneous and especially intranasal routes need substantially higher doses than intravenous to achieve the same GH response [12]. Route choice in the studies tracked the goal: subcutaneous for sustained dosing, intravenous for diagnostics and PK. ## Why bedtime administration was studied Research protocols used bedtime subcutaneous dosing to coincide with the post-sleep-onset GH pulse. The body's largest endogenous GH pulse occurs shortly after sleep onset, so GHRH research used nocturnal dosing to *augment* that natural pulse rather than introduce an out-of-phase stimulus [10]. Single nightly injections of GHRH(1-29) in healthy elderly men were specifically studied for their effect on the GH/IGF-1 axis [10], and GHRH's sleep-endocrine effects are known to depend on the time of administration [12]. This describes how studies were designed; it is not a usage recommendation. ## Timing of administration in the studies The timing logic in the studies is consistent: align the stimulus with the body's own rhythm. The largest natural GH pulse follows sleep onset, GHRH's effects are time-of-administration dependent [12], and the pediatric efficacy protocol dosed at bedtime [1]. Where studies departed from nocturnal dosing — the twice-daily older-men protocol, the intravenous diagnostic and PK work — the goal was different (steady-state GH/IGF-1 elevation, or acute stimulation testing) [2][3]. Timing in the record is an endpoint-driven design choice, reported here as such. ## Treatment durations used in the research Study durations varied widely, so there is no single "enough" window. The older-men GH/IGF-1 study ran 14 days [2]; the GHRH-analog cognition trial ran 20 weeks [6]; pediatric growth therapy operated on a year-scale, with the height-velocity result measured over the first year [1]. Outcomes were endpoint- and population-specific: a two-week course was sufficient to move GH/IGF-1 in older men, but a cognition or growth endpoint required months to years. Duration in this literature is defined by the question being asked, not by a fixed protocol. ## Formulation and stability notes Sermorelin acetate is supplied as a lyophilized (freeze-dried) powder because aqueous peptide solutions are susceptible to degradation. It is reconstituted with sterile diluent and, once reconstituted, typically refrigerated. Compounded preparations are prepared under USP <797> sterile-compounding standards. The very low intranasal bioavailability (~3-5%) reported for GHRH(1-29) [3] is the same pharmacology that underlies criticism of oral, sublingual, and troche "sermorelin" formulations — peptides are degraded in the gut and poorly absorbed across mucosa, so non-injectable formats face a steep bioavailability problem. --- A premium-Swiss reading of the GHRH(1-29) record — the pulsatile-GH mechanism, the studied doses, and the WADA-prohibited status set in disciplined whitespace and cited to source; no clinic behind the monograph and nothing here dispensed, prescribed, or sold.